The invention relates to a gas bag protective device comprising a gas bag made of at least two opposite fabric layers, which delimit at least one chamber which is able to be filled with gas, the fabric layers consisting of warp- and weft threads, the gas bag having at least one spacer which is connected with the fabric layers and in the inflated state limits the spacing of the fabric layers from each other and having at least two anchoring points on which it is to be fastened to the vehicle and between which it is tensioned in the inflated state.
A gas bag protective device is known for example from the U.S. Pat. No. 5, 464,250. Acting as a spacer here is a fabric section running in a zig-zag shape, which is sewn to the fabric layers at the edge sections. This spacer brings it about that the gas bag does not bulge out too much, i.e. it does not assume too great a thickness between its edges. Other types of spacer are so-called tethers which are sewn at their ends to the fabric layers and limit the spacing locally. The mounting of spacers is very expensive and costly and impedes the turning over of the gas bag after sewing. The arrangement of the spacers is therefore very complicated and, for manufacturing reasons, is not possible at any desired location. On the other hand, the inflated gas bags would become unnecessarily thick without the spacers, which raises problems. The optimum restraint requires, in part, no extreme thickness of the gas bag, so that only unnecessarily too much gas is needed to fill the gas bag so that it is taut. In addition, with an increasing thickness, the danger is also increased for the occupant to be hit by the unfolding gas bag.
For this reason, side gas bags, so-called window bags, are produced, which have numerous parallel, narrow chambers. Here, the fabric layers are woven with each other in one piece on the outer periphery of the gas bag and between the chambers. The numerous, in part elongated chambers, having a low cross-section, can increase the inflation time of the gas bag. In addition, they require an exact conducting of gas to the chambers themselves, e.g. a gas lance which extends along the roof frame.
From the U.S. Pat. No. 5,322,322 a tube-shaped, elongated gas bag is known, which in the inflated state extends obliquely upwards from the lower region of the A-column up to the roof frame in the region of the rear passenger. The fabric material which is used runs here approximately at 45xc2x0 to the longitudinal extent, in order to achieve a shortening and tensioning effect. Owing to this thread path, the gas bag can distinctly expand in cross-section on inflation and can become shortened in longitudinal direction. Through the intensive expansion and through the extreme movement of the threads, a second gas bag housed in the actual gas bag must provide for the necessary gas-tightness.
The invention provides a gas bag protective device with a gas bag which is distinguished by spacers which are extremely simple and cheap to produce, the spacers also providing for the tensioning and affecting the flow within the gas bag less than bags known hitherto. In addition, the gas bag according to the invention is distinguished in that the spacers can be provided at any desired sites and in any desired number, without making the production of the gas bag distinctly more expensive or difficult. This is achieved in a gas bag protective device of the type initially mentioned in that the spacer is provided on an imaginary straight connecting line of anchoring points and brings about a tensioning of the gas bag between the anchoring points, the spacer being formed by some of the warp- and/or weft threads which, in relation to the inflated state, leave the area formed by their associated fabric layer and extend in the direction toward the opposite fabric layer and are connected with warp- and/or weft threads of the opposite fabric layer. In the gas bag according to the invention, the spacer is formed by some warp- and/or weft threads which leave the fabric composite, as it were, and extend in the direction toward the opposite fabric layer. The spacer is therefore not a separate part to be fastened to the fabric layers, but rather it is an integral component of the fabric layers. The technique of partially weaving fabric layers with each other allows the spacers to be positioned at any desired sites. Furthermore, the individual warp- and/or weft threads, in the region in which they act as spacers, only slightly impede the flow within the gas bag, because it is not compulsory for them to be constructed as a two-dimensional fabric in the region of the spacer. Thus the gas can flow through between the individual threads and lead to a rapid unfolding of the gas bag. By the cheap and variable technique of weaving with each other in one piece, through the invention for the first time almost mattress-like gas bags having a large area can be produced at a favorable cost. The spacer or spacers provide for a shortening of the gas bag in the region of the straight connecting line by threads, as viewed in a section along the straight connecting line, leaving the fabric composite in the direction toward the interior of the gas bag, whereby a longer distance for the threads is produced than for threads which do not leave the fabric composite.
The warp- and/or weft threads functioning as spacers, after leaving the area formed by their associated fabric layer (usually the outer wall of the gas bag) and after formation of the spacer, can merge into the opposite fabric layer, hence becoming an integral component of this fabric layer. In addition, however, after formation of the spacer, the spacers can run back again to the fabric layer associated with them and merge integrally into it. Then, however, they must be connected in the region of the spacer with warp- and/or weft threads of the opposite fabric layers. This can be achieved for example in that also from the opposite fabric layer, warp- and/or weft threads emerge from the composite and become connected between the two outer walls of the gas bag with the warp- and/or weft threads emerging from the fabric composite of the opposite fabric layer.
In this way, for example, spacers can be produced which form an H-, X- or Y-shape in cross-section.
The warp- and/or weft threads which form the spacer are missing in the region of the spacer in the fabric layer associated with them. The fabric layer therefore becomes less gas-tight at this point. This can be used deliberately to give the gas bag outer wall a predetermined gas permeability. When, however, the gas permeability becomes too great, the fabric layer which makes available the warp- and/or weft threads, can also be coated at least in the region of the spacer. Inter alia in side gas bags which are to be filled so as to be taut as long as possible, the fabric layers are preferably coated externally with a foil. In so doing, also numerous spacers can be provided, because it is no longer disadvantageous with respect to the gas permeability through coating with a foil that the outer wall only has a few threads in the region of the spacers. The fabric itself therefore forms substantially only a support structure and the actual gas-tightness is achieved by the foil.
When the gas bag is a side gas bag having a large area and has several chambers which are formed by weaving the opposite fabric layers in one piece, in addition the spacers described above are provided inside the chambers. Although the chambers themselves have a small cross-section, the thickness of the gas bag can be further reduced by the spacers and can be reduced to the extent which is sufficient for restraint.
The spacers can run in an elongated manner and, for example, linearly, i.e. can form an elongated, gas-permeable wall. However, the spacers can also be only punctiform or ring-shaped, similar to in the case of a bed mattress, where buttons, visible from the exterior, form the end of spacers.
With respect to the annular construction, it is to be explained in further detail that this annular shape is formed by exit- and/or entry points, at which threads for forming a spacer run from or into a fabric layer, by the exit- and/or entry points complementing each other to form a ring, preferably a circular ring. The fabric layer with the exit-/entry points complementing each other to form a ring has in the inflated state of the gas bag a dome-, cupola- or spherical segment-shaped form. When the exit points lie very close to each other, the ring can be filled, so that the exit points of a spacer complement each other to form a point. In order to achieve a sufficient tensioning effect, preferably numerous successive rings are provided, lying in a row, the row being aligned to the straight connecting line. When a cushion-shaped or mattress-shaped gas bag with a large area is used, several successive rows can be provided, preferably parallel rows of rings. If the rings of adjacent rows are staggered laterally with respect to each other, the gas bag is formed in the region of the spacers by dome-, cupola- or spherical segment-shaped regions even possibly merging into each other.
The protective device according to the invention is preferably a side gas bag protection device to protect the occupant""s head, which extends to the side of the occupant""s head in the region of his possible sitting postures and largely covers the side window and extends straight across the side window. Along the straight connecting line of the anchoring points which are to be provided at opposite ends of the gas bag, numerous spacers are arranged in series adjacent to each other, the entire section of the straight connecting line in the region of a chamber or of several chambers being formed by numerous spacers which are arranged in series adjacent to each other.
An embodiment makes provision that the warp- and/or weft threads extend parallel to the straight connecting line.